To be sure, most of the fighting in Syria pits the regime's infantry and mechanized forces against insurgent foot soldiers armed with rifles, machine guns and, if they're lucky, a rocket or two. Increasingly Assad's forces have deployed Russian-made Hip helicopters armed with rockets. Damascus attempted to acquire new Hind attack copters from Russia last month, but Moscow bowed to international pressure and recalled the cargo ship transporting the Hinds.

The rebels aren't defenseless. As the aerial threat escalated, the Free Syrian Army fought back with heavy machine guns and captured government anti-aircraft weapons, apparently destroying at least one helicopter, as depicted in the video above. The rebel arsenal possibly includes a captured ZSU-23-4, a fast-firing, gun-armed vehicle that was one of the most fearsome aircraft-killers of the Cold War. And the opposition has been building up its weapons expertise on Facebook and YouTube.

In general, Assad's jets fly too high and too fast for the rebels to easily hit, though insurgent fighters did manage to destroy at least one aged MiG-23 on the ground by sneaking up to the airfield and firing a rocket-propelled grenade. But the speed and altitude that protects the jets also makes it difficult for them to effectively strike rebel positions. To accurately hit Taliban fighters in Afghanistan, the U.S. Air Force relies on highly-trained observers on the ground. It's unlikely Damascus employs similar specialists.

Some reporters covering the fighting are skeptical that Syrian planes have even fired ordnance at all. The Associated Press described jets swooping over Aleppo and breaking the sound barrier as a bloodless "show of force" – a favorite tactic of American warplanes in Afghanistan. The AP attributed widespread destruction in the city to helicopters and artillery.

The Syrian air force suffers "low operational readiness, low combat sortie rates and an over-centralized battle management system," CSIS concluded. Morale among pilots could also be low. One flier, Col. Hassan Hammadeh, defected to Jordan in his MiG-21 last month.

An air force that decrepit gets used rarely – and only when the stakes are high. But that doesn't mean aerial attacks on insurgent forces actually work.